Cisco Security Advisory
Click Icon to Copy Verbose Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:X/RL:X/RC:X
-
Multiple vulnerabilities in Cisco IOS XR Software could allow an authenticated, local attacker to execute commands as root on an underlying operating system or gain full administrative control of an affected device.
For more information about these vulnerabilities, see the Details section of this advisory.
Cisco has released software updates that address these vulnerabilities. A workaround is available for one of the vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-privesc-bF8D5U4WThis advisory is part of the March 2026 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication.
-
Vulnerable Products
The vulnerability described in CVE-2026-20040 affects Cisco IOS XR Software, regardless of device configuration.
The vulnerability described in CVE-2026-20046 affects Cisco IOS XRv 9000 Routers, regardless of device configuration.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect the following Cisco products:
- IOS Software
- IOS XE Software
- NX-OS Software
-
The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit the other vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerability.
Details about the vulnerabilities are as follows:
CVE-2026-20040: Cisco IOS XR Software CLI Privilege Escalation Vulnerability
A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to execute arbitrary commands as root on the underlying operating system of an affected device.
This vulnerability is due to insufficient validation of user arguments that are passed to specific CLI commands. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the prompt. A successful exploit could allow the attacker to elevate privileges to root and execute arbitrary commands on the underlying operating system.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwp84685, CSCwp27221, CSCwp30135, CSCwp33034, CSCws24740, CSCws24717, CSCwp33021, CSCwp32614, CSCwp30142, CSCws24696, CSCwp30149, CSCwp35627, CSCwp32629, CSCwp30146, CSCwp33030
CVE ID: CVE-2026-20040
Security Impact Rating (SIR): High
CVSS Base Score: 8.8
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HCVE-2026-20046: Cisco IOS XR Software CLI Privilege Escalation Vulnerability
A vulnerability in task group assignment for a specific CLI command in Cisco IOS XR Software could allow an authenticated, local attacker to elevate privileges and gain full administrative control of an affected device.
This vulnerability is due to incorrect mapping of a command to task groups within the source code. An attacker with a low-privileged account could exploit this vulnerability by using the CLI command to bypass the task group–based checks. A successful exploit could allow the attacker to elevate privileges and perform actions on an affected device without authorization checks.
Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.
Bug ID(s): CSCwp87543
CVE ID: CVE-2026-20046
Security Impact Rating (SIR): High
CVSS Base Score: 8.8
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
-
CVE-2026-20040: There are no workarounds that address this vulnerability.
CVE-2026-20046: There is a workaround only for devices that have TACACS+ authentication, authorization, and accounting (AAA) command authorization configured. Administrators can use this feature to permit access only to commands that non-administrative users require and deny access to all other commands.
While this workaround has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.
-
Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate these vulnerabilities and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
Fixed Releases
In the following table, the left column lists Cisco software releases. The center and right columns indicate whether a release is affected by the vulnerabilities that are described in this advisory and the first release that includes the fix for these vulnerabilities. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.
Cisco IOS XR Software Release First Fixed Release for CVE-2026-20040 First Fixed Release for CVE-2026-20046 25.1 and earlier Migrate to a fixed release. Migrate to a fixed release. 25.2 25.2.21 (Mar 2026) 25.2.2 25.3 Migrate to a fixed release. Not affected. 25.4 25.4.2 (Mar 2026) Not affected. 26.1 Not affected. Not affected. SMUs are also available to address these vulnerabilities. Customers who require SMUs for platforms or releases that are not available are advised to contact their support organization. For more information on finding which SMUs may have been published for these vulnerabilities, see the Download section of Understand Cisco IOS XR Software Maintenance Updates (SMUs).
Note: The SMU for Cisco bug ID CSCws61542 includes the fixes for CSCwp30135 and CSCws24717. The SMU for Cisco bug ID CSCws35777 includes the fix for CSCwp33034.
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
-
The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
-
CVE-2026-20040: This vulnerability was found during internal security testing by Tristan Van Egroo of the Cisco Advanced Security Initiatives Group (ASIG).
CVE-2026-20046: This vulnerability was found during internal security testing.
-
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
-
Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2026-MAR-11
-
SOFTWARE DOWNLOADS AND TECHNICAL SUPPORT
The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool. Please note that customers may download only software that was procured from Cisco directly or through a Cisco authorized reseller or partner and for which the license is still valid.
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC). Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.
When considering software upgrades, customers are advised to regularly consult the advisories for the relevant Cisco products to determine exposure and a complete upgrade solution. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
LEGAL DISCLAIMER DETAILS
CISCO DOES NOT MAKE ANY EXPRESS OR IMPLIED GUARANTEES OR WARRANTIES OF ANY KIND, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, CISCO DOES NOT GUARANTEE THE ACCURACY OR COMPLETENESS OF THIS INFORMATION. THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
Copies or summaries of the information contained in this Security Advisory may lack important information or contain factual errors. Customers are advised to visit the Cisco Security Advisories page for the most recent version of this Security Advisory. The Cisco Product Security Incident Response Team (PSIRT) assesses only the affected and fixed release information that is documented in this advisory. See the Cisco Security Vulnerability Policy for more information.